1/*
2 * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 2.
7 */
8
9#include <linux/clk.h>
10#include <linux/err.h>
11#include <linux/io.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/platform_device.h>
15#include <linux/pwm.h>
16
17#define PWM_CONTROL		0x000
18#define PWM_CONTROL_SHIFT(x)	((x) * 8)
19#define PWM_CONTROL_MASK	0xff
20#define PWM_MODE		0x80		/* set timer in PWM mode */
21#define PWM_ENABLE		(1 << 0)
22#define PWM_POLARITY		(1 << 4)
23
24#define PERIOD(x)		(((x) * 0x10) + 0x10)
25#define DUTY(x)			(((x) * 0x10) + 0x14)
26
27#define MIN_PERIOD		108		/* 9.2 MHz max. PWM clock */
28
29struct bcm2835_pwm {
30	struct pwm_chip chip;
31	struct device *dev;
32	unsigned long scaler;
33	void __iomem *base;
34	struct clk *clk;
35};
36
37static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
38{
39	return container_of(chip, struct bcm2835_pwm, chip);
40}
41
42static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
43{
44	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
45	u32 value;
46
47	value = readl(pc->base + PWM_CONTROL);
48	value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
49	value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
50	writel(value, pc->base + PWM_CONTROL);
51
52	return 0;
53}
54
55static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
56{
57	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
58	u32 value;
59
60	value = readl(pc->base + PWM_CONTROL);
61	value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
62	writel(value, pc->base + PWM_CONTROL);
63}
64
65static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
66			      int duty_ns, int period_ns)
67{
68	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
69
70	if (period_ns <= MIN_PERIOD) {
71		dev_err(pc->dev, "period %d not supported, minimum %d\n",
72			period_ns, MIN_PERIOD);
73		return -EINVAL;
74	}
75
76	writel(duty_ns / pc->scaler, pc->base + DUTY(pwm->hwpwm));
77	writel(period_ns / pc->scaler, pc->base + PERIOD(pwm->hwpwm));
78
79	return 0;
80}
81
82static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
83{
84	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
85	u32 value;
86
87	value = readl(pc->base + PWM_CONTROL);
88	value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
89	writel(value, pc->base + PWM_CONTROL);
90
91	return 0;
92}
93
94static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
95{
96	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
97	u32 value;
98
99	value = readl(pc->base + PWM_CONTROL);
100	value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
101	writel(value, pc->base + PWM_CONTROL);
102}
103
104static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
105				enum pwm_polarity polarity)
106{
107	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
108	u32 value;
109
110	value = readl(pc->base + PWM_CONTROL);
111
112	if (polarity == PWM_POLARITY_NORMAL)
113		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
114	else
115		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
116
117	writel(value, pc->base + PWM_CONTROL);
118
119	return 0;
120}
121
122static const struct pwm_ops bcm2835_pwm_ops = {
123	.request = bcm2835_pwm_request,
124	.free = bcm2835_pwm_free,
125	.config = bcm2835_pwm_config,
126	.enable = bcm2835_pwm_enable,
127	.disable = bcm2835_pwm_disable,
128	.set_polarity = bcm2835_set_polarity,
129	.owner = THIS_MODULE,
130};
131
132static int bcm2835_pwm_probe(struct platform_device *pdev)
133{
134	struct bcm2835_pwm *pc;
135	struct resource *res;
136	int ret;
137
138	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
139	if (!pc)
140		return -ENOMEM;
141
142	pc->dev = &pdev->dev;
143
144	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
145	pc->base = devm_ioremap_resource(&pdev->dev, res);
146	if (IS_ERR(pc->base))
147		return PTR_ERR(pc->base);
148
149	pc->clk = devm_clk_get(&pdev->dev, NULL);
150	if (IS_ERR(pc->clk)) {
151		dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk));
152		return PTR_ERR(pc->clk);
153	}
154
155	ret = clk_prepare_enable(pc->clk);
156	if (ret)
157		return ret;
158
159	pc->scaler = NSEC_PER_SEC / clk_get_rate(pc->clk);
160
161	pc->chip.dev = &pdev->dev;
162	pc->chip.ops = &bcm2835_pwm_ops;
163	pc->chip.npwm = 2;
164
165	platform_set_drvdata(pdev, pc);
166
167	ret = pwmchip_add(&pc->chip);
168	if (ret < 0)
169		goto add_fail;
170
171	return 0;
172
173add_fail:
174	clk_disable_unprepare(pc->clk);
175	return ret;
176}
177
178static int bcm2835_pwm_remove(struct platform_device *pdev)
179{
180	struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
181
182	clk_disable_unprepare(pc->clk);
183
184	return pwmchip_remove(&pc->chip);
185}
186
187static const struct of_device_id bcm2835_pwm_of_match[] = {
188	{ .compatible = "brcm,bcm2835-pwm", },
189	{ /* sentinel */ }
190};
191MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
192
193static struct platform_driver bcm2835_pwm_driver = {
194	.driver = {
195		.name = "bcm2835-pwm",
196		.of_match_table = bcm2835_pwm_of_match,
197	},
198	.probe = bcm2835_pwm_probe,
199	.remove = bcm2835_pwm_remove,
200};
201module_platform_driver(bcm2835_pwm_driver);
202
203MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be");
204MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
205MODULE_LICENSE("GPL v2");
206